1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Oksanka [162]
3 years ago
5

Solve the systems by the addition method x - 2y = - 4 2x + y = 7

Mathematics
1 answer:
vfiekz [6]3 years ago
5 0
<h2>x - 2y = -4</h2><h2>2x + y = 7</h2><h2 />

To solve this system of equations by addition, our first goal is to cancel

out one of the variables by adding the two equations together.

However, if we add these two equations together right away, nothing

will cancel so we need to set things up so a variable will cancel.

Notice that we have an 2x in our second equation.

If we had a -2x in our first equation, then the x's would cancel out.

In order to create a -2x in the first equation, we simply

multiply both sides of the first equation by -2.

So we have (-2)(x - 2y) = (-4)(-2) which can be rewritten as -2x + 4y = 8.

Now rewrite both equations, as shown below.

<h2>-2x + 4y = 8</h2><h2>2x + y = 7</h2><h2 />

Now when we add the equations together, the x terms

will cancel out and we're left with 5y = 15.

Dividing both sides by 5, <em>y = 3</em>.

To solve for x, plug a 3 in for y in either one of our 2 original equations.

So let's go with our second equation.

Plugging a 3 in for y, we get 2x + (3) = 7.

Now subtract 4 from both sides to get 2x = 4.

Dividing both sides by 2, we fid that <em>x = 2</em>.

Since x = 2 and y = 3, our answer is the ordered pair (2, 3).

You might be interested in
Matthew and Ava have some money in the ratio 5:2. If Matthew gives $78 to Ava they will have the same amount of money. How much
MaRussiya [10]

Answer:

is d

Step-by-step explanation:

5 0
3 years ago
Why is 97 the answer
Kazeer [188]
It could also be 31!
7 0
3 years ago
Read 2 more answers
99 POINT QUESTION, PLUS BRAINLIEST!!!
Elden [556K]
We draw region ABC. Lines that connect y = 0 and y = x³ are vertical so:
(i) prependicular to the axis x - disc method;
(ii) parallel to the axis y - shell method;
(iii) parallel to the line x = 18 - shell method.

Limits of integration for x are easy x₁ = 0 and x₂ = 9.
Now, we have all information, so we could calculate volume.

(i)

V=\pi\cdot\int\limits_a^bf^2(x)\, dx\qquad\implies \qquad a=0\qquad b=9\qquad f(x)=x^3


V=\pi\cdot\int\limits_0^9(x^3)^2\, dx=\pi\cdot\int\limits_0^9x^6\, dx=\pi\cdot\left[\dfrac{x^7}{7}\right]_0^9=\pi\cdot\left(\dfrac{9^7}{7}-\dfrac{0^7}{7}\right)=\dfrac{9^7}{7}\pi=\\\\\\=\boxed{\dfrac{4782969}{7}\pi}

Answer B. or D.

(ii)

V=2\pi\cdot\int\limits_a^bx\cdot f(x)\, dx


V=2\pi\cdot\int\limits_0^{9}(x\cdot x^3)\, dx=2\pi\cdot\int\limits_0^{9}x^4\, dx=&#10;2\pi\cdot\left[\dfrac{x^5}{5}\right]_0^9=2\pi\cdot\left(\dfrac{9^5}{5}-\dfrac{0^5}{5}\right)=\\\\\\=2\pi\cdot\dfrac{9^5}{5}=\boxed{\dfrac{118098}{5}\pi}

So we know that the correct answer is D.

(iii)
Line x = h

V=2\pi\cdot\int\limits_a^b(h-x)\cdot f(x)\, dx\qquad\implies\qquad h=18


V=2\pi\cdot\int\limits_0^9\big((18-x)\cdot x^3\big)\, dx=2\pi\cdot\int\limits_0^9(18x^3-x^4)\, dx=\\\\\\=2\pi\cdot\left(\int\limits_0^918x^3\, dx-\int\limits_0^9x^4\, dx\right)=2\pi\cdot\left(18\int\limits_0^9x^3\, dx-\int\limits_0^9x^4\, dx\right)=\\\\\\=2\pi\cdot\left(18\left[\dfrac{x^4}{4}\right]_0^9-\left[\dfrac{x^5}{5}\right]_0^9\right)=2\pi\cdot\Biggl(18\biggl(\dfrac{9^4}{4}-\dfrac{0^4}{4}\biggr)-\biggl(\dfrac{9^5}{5}-\dfrac{0^5}{5}\biggr)\Biggr)=\\\\\\

=2\pi\cdot\left(18\cdot\dfrac{9^4}{4}-\dfrac{9^5}{5}\right)=2\pi\cdot\dfrac{177147}{10}=\boxed{\dfrac{177147\pi}{5}}

Answer D. just as before.

6 0
3 years ago
What’s the equation for this table?<br> X : -4, -3, -2, -1<br> Y: -11, -9, -7, -5
tankabanditka [31]

in slope intercept form :

y = 2x - 19

( I think )

8 0
3 years ago
What is 7/10-14/100 in simplest form
quester [9]
\frac{7}{10}-\frac{14}{100}=0.7-0.14=0.70-0.14=0.56
3 0
3 years ago
Read 2 more answers
Other questions:
  • Factor out the coefficient of the variable term The expression 1/10k-7/10 factored is
    6·1 answer
  • Four diners have ordered a platter of desserts. The platter holds 8 chocolate chip cookies and 4 slices of chocolate cheesecake.
    14·1 answer
  • Can someone please help me
    6·1 answer
  • WILL GIVE BRAINLIEST!! PLEASE SHOW YOUR WORK!
    9·1 answer
  • Let angle 1 and angle 2 be complementary. If má 1 = 4x +3 and m42 = x + 2, find the measure
    8·2 answers
  • Help<br>I'll give brainliest​
    15·2 answers
  • Need help ASAP! Due in 15 minutes
    8·2 answers
  • What is the answer<br><img src="https://tex.z-dn.net/?f=%20%5Cfrac%7B3%7D%7B6%7D%20%20%2B%20%20%5Cfrac%7B12%7D%7B12%7D%20" id="T
    13·1 answer
  • on a map 2 inches equals 40 miles. if two cities are 15 miles apart what is the distinace between them on a map
    9·2 answers
  • The variable a varies inversely with b. The value of a is 2 when b = 40. Find the constant of variation (k). I will give brainli
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!